Paste or drop two texts, and see exactly where they differ.
It is the view WinMerge made familiar: the two side by side, a changed line
tinted, and inside a changed line the actual words that moved a stronger
shade, so the eye lands on the one character that matters instead of a wall of
red. Contracts with a clause quietly reworded, two config files that should
match, a paragraph before and after an edit: this is for telling whether two
things really are the same.
Is this actually private?
Nothing is uploaded. Static page, no endpoint, no account. Both texts are compared in this tab and never leave it; there is no server to send them to, which is a rule your browser enforces here, not a promise.
It compares text, not layout. A file is read as text. Two PDFs or two Word documents will not compare usefully here, because their bytes are not their words; convert them to text first, or use the converter. Plain text, code, CSV, configuration, Markdown: those are what this is for.
The algorithm is the real one. It is Myers' diff, the shortest-edit-script method that git and the diff command use, run first over the lines and then over the characters of a line that changed. It is written here, in a few hundred lines, rather than pulled from a library, and the tests check it against known cases.
Ignore whitespace and ignore case change the comparison, not your text. They decide what counts as a difference; the lines shown are always your originals. Ignore whitespace treats runs of spaces and tabs as equal and trims the ends, which is what you want when two files differ only in indentation.
Very large files are real work. The whole of both sits in memory and the diff is quadratic in the worst case, so two ten-thousand-line files are fine and two enormous logs may make a phone think. It is a comparison tool, not a big-data one.
Line endings are normalised. A file saved on Windows (CRLF) and one saved on a Mac or Linux (LF) are not reported as different on every single line; the endings are levelled before comparing, because that difference is almost never the one you are looking for.
Nothing here is for sale, nothing is tracked, and there is no account to make.
If something saved you an hour: 83TQcTwusSQ4WKbPQE5osrF3cR4GWe2zmcNWeozK6BSqHSaeLvjUVe476ouVwLKn1uVwEFcbJQvnme7W6dTV5SB93x45DEy
You can
check that address here before sending anything.